1. Field of the Invention
The present invention relates to a liquid droplet ejection apparatus that ejects functional liquid from a functional liquid droplet ejection head onto a workpiece while moving a head unit including the functional liquid droplet ejection head relative to the workpiece, a method for manufacturing an electro-optic device, an electro-optic apparatus, and an electronic equipment.
2. Description of the Related Art
There is known a liquid droplet ejection apparatus which is used to manufacture a variety of products (e.g., a color filter of a liquid crystal display device) by a liquid droplet ejection method using a functional liquid droplet ejection head. The liquid droplet ejection apparatus includes an X-axis direction moving mechanism which moves a substrate transport table (set table), on which a substrate (workpiece) is set, in the X-axis direction and an Y-axis direction moving mechanism which moves a head unit, on which the functional liquid droplet ejection head is mounted, in the Y-axis direction. The area where the moving area of the head unit and the moving area of the substrate transport table overlap is a liquid droplet ejection area where drawing (picturing) can be carried out on the substrate. By driving the ejection of the functional liquid droplet ejection head while relatively moving the head unit and the substrate, the liquid droplet ejection apparatus can draw a predetermined drawing pattern on the substrate located in the liquid droplet ejection area.
The liquid droplet ejection apparatus also includes a periodic flushing unit, which is one of maintenance units for maintaining the functional liquid droplet ejection head. A periodic flushing box receives forcible ejection (periodic flushing) from all ejection nozzles of the functional liquid droplet ejection head. The forcible ejection (or waste ejection) is carried out in order to prevent clogging of the functional liquid droplet ejection head while no drawing process is carried out to the workpiece and in order to stabilize the amount of functional liquid ejected from the functional liquid droplet ejection head. Accordingly, the periodic flushing box includes a liquid reservoir for receiving the functional liquid of the forcible ejection. The liquid reservoir is located in the moving area of the head unit moved by the Y-axis direction moving mechanism and outside the moving area of the substrate transport table. When carrying out the periodic flushing ejection, the head unit is moved to a position immediately above the liquid reservoir (see, for example, JP-A-2004-202325).
Since the ejection nozzle of the functional liquid droplet ejection head is very small, even a short stop of an ejection mechanism may cause clogging of the ejection nozzle or may cause the variation in the amount of ejected functional liquid. Accordingly, it is desirable that the nonoperating time of the functional liquid droplet ejection head is reduced as much as possible by repeatedly ejecting the functional liquid from the functional liquid droplet ejection head even when the drawing process is not carried out on the workpiece. However, in the known liquid droplet ejection apparatuses, since a liquid reservoir of the periodic flushing unit is located outside the moving area of the substrate transport table, the Y-axis direction moving mechanism needs to move the head unit located in a liquid droplet ejection area to the liquid reservoir of the periodic flushing unit when carrying out periodic flushing after a drawing process. In addition, when carrying out another drawing process, the Y-axis direction moving mechanism needs to move the head unit to the liquid droplet ejection area again. Therefore, the known liquid droplet ejection apparatus requires a long time from the completion of the drawing process to the start of the periodic flushing process and from the completion of the periodic flushing process to the start of another drawing process. That is, since the stop time of the ejection of the functional liquid droplet ejection head increases, an ejection defect of the functional liquid droplet ejection head tends to occur. Furthermore, the round-trip time of the head unit moving between the liquid droplet ejection area and the liquid reservoir for each drawing process increases the tact time of total processing, thus decreasing the processing efficiency.